M925A2 Transmission losing oil

[idbankrman]

I just picked up an M925A2 in Columbia SC and drove it over three days to Denver. Truck worked great except for Throttle Control solenoid falling apart and the transmission using a **** of a lot of oil. I put 11 quarts of 15W45 in it over the course of the drive. I drove the truck mostly flat out at 55MPH. I have since read that I probably should have been a little easier on her. Anyway the oil seems to be coming from the vent line and I'm wondering if it is just normal when driving so hard for it to vent oil?

 

[TacticalDoc]

Does it have a fording kit? If it does then make sure its off. Also, if the trans, t case or fuel tank are over filled it will leak into the air box. This can be dangerous because it can get sucked into the motor and you can get a run away motor. I bypassed my lines.

see here
http://www.steelsoldiers.com/showthread.php?115884-Air-intake-stack-vents-and-bypassing-axles

 

[61sleepercab]

Food for thought:
Did trans temperature gauge work during trip and was it hot? Smell Hot Oil smell?
Does vent line connect to a possible vacuum source when running full out? Was truck burning extra smoke? if vent goes to air intake stack is air filter wet?
Put a big piece of cardboard under the trans and let it set to see if drip seen....... Try starting up and idle a while and warm up and check for leaks.

I am no expert but either fluid is some how leaking out or being sucked out at high road speed which means high fluid temps, high air flow in air cleaner, or leak when output shafts are turning fast and seal gets hot or soft????

 

[Rmtaunton]

I could be way wrong as I don't have a 9 series , but two things , a 925 is an automatic and should use a fluid that supports it, check and make sure you are using right fluid , and second if it is coming out the vent line which is on top and obviously venting , make sure your level is correct . And good luck

 

[MtnSnow]

Make sure your checking the level correctly too

 

[TacticalDoc]

Best thing to do is bypass all 3 of the hoses going to the air box. Then you can see which is leaking and you don't get a run away motor.

 

[juanprado]

check coolant in reservoir in case T cooler is leaking internally.

 

[idbankrman]

The TM lists four oils for the transmission. Only one is a normal transmission fluid, Dexron III. All the others are engine oils. At least that is what I believe "OE HDO 15W40" means? The oil that was in the transmission when I picked it up was caramel in color like brand new engine oil so I went with the 15W40 engine oil. Several people told me that this is fairly common in heavy equipment transmissions. I'm checking the oil with the engine running and truck and trans at normal operating temp. The transmission never did get hot it just wouldn't shift into 4th or 5th gear as the oil got low. The transmission doesn't leak when the truck is idling or not running. The output shaft seal does not appear to be leaking nor is there any evidence around the area where the engine and transmission mate. Coolant looks normal. The vent hose I am looking at is open and pointing straight down towards the ground. So I will check and see if the hose that goes to the air box is actually hooked up when it gets warmer. Most of the oil that came out of the transmission appears to be all over the bottom of the truck and looks as though it was applied as a very fine mist. It's very cold right now so I am awaiting warmer weather to investigate further.

 

[TacticalDoc]

I spoke with 2 different Allison mechanics. They said that Dex 3 is not recommended. I told them the trans model number and they said it's not an electric trans and I should keep changing it with the 15w40 motor oil that is already in it.

 

[idbankrman]

Ok thanks I will keep putting 15W40 in it.

 

[1 Patriot-of-many]

Like someone else said. Check the level carefully as to TM's. It's easy to get a false reading with all these trucks. I use what was in the vehicle, usually oil. My wrecker apparently has dexron, hopefully I remember and don't mix it with oil.

 

[idbankrman]

The weather warmed up today so I got to work on the transmission leak problem After wiping it down and fixing a coolant leak that was dripping onto the transmission it now looks like the leak must be from the left side of the transmission at the pan gasket. I have not checked the air box yet to see if it has oil in it. The pan gasket does not leak when the truck is shut down but there is oil present and at a control shaft that comes out of the transmission on the left side. One thing I also found was a missing drain plug in the engine to transmission adaptor (Bell Housing?) There are two drain plugs in it one in front of the other and the forward one is missing but there does not appear to be any oil coming out of that point.

 

[73m819]

The weather warmed up today so I got to work on the transmission leak problem After wiping it down and fixing a coolant leak that was dripping onto the transmission it now looks like the leak must be from the left side of the transmission at the pan gasket. I have not checked the air box yet to see if it has oil in it. The pan gasket does not leak when the truck is shut down but there is oil present and at a control shaft that comes out of the transmission on the left side. One thing I also found was a missing drain plug in the engine to transmission adaptor (Bell Housing?) There are two drain plugs in it one in front of the other and the forward one is missing but there does not appear to be any oil coming out of that point.

Think the learning curve is a little FLAT here

 

[idbankrman]

Well I admit being completely unfamiliar with this truck but what may appear FLAT for some is fairly steep for me. This truck was refurbished by the Red River Depot. So far I am not impressed with their work. The truck was shipped from Texarkana to Columbia SC and never used. The original shipping documents were still in the cab when I picked it up. So far it has had 3 coolant leaks from insufficiently tightened clamps, the transmission mystery fluid consumption we have been discussing, a rear axle pinion shaft leak, a bent rear axle spring shackle mounting bolt (it will have to be cut and pounded out, the nut is already missing), a broken throttle stop solenoid arm (welded this back together today), and a missing power steering pump reservoir lid gasket. From my experience receiving Air Force aircraft from depot level maintenance this would be about par. I guess I should not have expected better from the Army

 

[M35A2-AZ]

a There are two drain plugs in it one in front of the other and the forward one is missing but there does not appear to be any oil coming out of that point.

The one hole in the bell housing should be open, the other one with the plug is just a holder hole for the drain plug.
You move it over to the open hole when you have to go into water.

 

[TacticalDoc]

Divert the hoses from the air box then seal the air box with gasket maker.

As far as the drain plug on the bell housing goes...leave it in the holder. do not plug it up unless you go deep water fording. I plan on putting an elbow with ball valve on it later to make this easier.

It's not letting me post pictures but if you want pictures of how I diverted the air box send me your email

 

[TacticalDoc]

 

[idbankrman]

Checked out the trans leak again today and found the transmission now way over full almost coming out the filler tube. So I am now convinced there is no leak. So what could be causing the fluid to get low while the truck is running and then flow back into the sump after it is shutdown for several days? Where does the oil go in the transmission if not back to the sump? Any ideas? I definitely read the dipstick correctly at all times. The oil is fairly easy to see in good light hot or cold.

 

[RustyM923]

Did you fill the trans when cold? This can cause over filling.

Change both of your filters...then check again. It could be a plugged filter restriction.

 

[idbankrman]

I filled it only after a hot check indicated it was low. Also I checked it because after stopping for fuel it would not shift into 4th or 5th. So I stopped and checked it and every time this happened. Over the course of 30 hours of driving the transmission showed low and wouldn't shift into 4 or 5 three times and adding oil up to the full mark got it shifting again every time. I assumed the oil was leaking out but it wasn't. Over the 30 hour drive I added about 9 quarts. At the start of the drive I checked the trans cold and it was at the cold full line. Now with the trans cold after the truck has been off for three days it is way over the full hot mark almost coming out the filler tube. So I am removing oil now and hoping I didn't cause some other damage but there is definitely something wrong. I think the oil is not returning to the sump except under pressure or slowly with truck sitting over time. I like the filter idea so I will change them.

The truck does not have a fording kit and the Air Box is dry. I'll consider the diversion of the vent lines but that is a project for another day. The only thing I want to check further here is that there is no restriction in the vent line from the transmission.

Thanks for the input about the plugs under the torque converter.